A security channel is provided for communication with an eight-bit, register-based, virtual machine. The virtual machine is placed into a direct mode, and then individual script instructions are sent to the virtual machine across the security channel for immediate interpreting by the virtual machine. The instructions are interpreted one by one as they are received. This feature can be used in debugging. This feature is usable in applications in which resident code is not required, but rather incoming script instructions are adequate to control device operation. A large memory is not required to store scripts, thereby reducing virtual machine system cost. Script instructions usable in the direct mode include instructions for loading a script API or machine code API onto the virtual machine from an external system, for loading a script, and for causing the virtual machine to output the contents of memory and/or internal registers to the external system.